vmstat: fix offset calculation on void*
authorWu Fengguang <fengguang.wu@intel.com>
Wed, 3 Nov 2010 17:56:49 +0000 (01:56 +0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 3 Nov 2010 18:39:58 +0000 (14:39 -0400)
commitff8b16d7e15a8ba2a6086645614a483e048e3fbf
treebba0a06fe931072b5794960e8dd928769ca58ce9
parent81a6cff678ecee7cdc0658285d3150660c07cfce
vmstat: fix offset calculation on void*

Fix regression introduced by commit 79da826aee6 ("writeback: report
dirty thresholds in /proc/vmstat").

The incorrect pointer arithmetic can result in problems like this:

  BUG: unable to handle kernel paging request at 07c06d16
  IP: [<c050c336>] strnlen+0x6/0x20
  Call Trace:
   [<c050a249>] ? string+0x39/0xe0
   [<c042be6b>] ? __wake_up_common+0x4b/0x80
   [<c050afcc>] ? vsnprintf+0x1ec/0x380
   [<c04b380e>] ? seq_printf+0x2e/0x60
   [<c04829a6>] ? vmstat_show+0x26/0x30
   [<c04b3bb6>] ? seq_read+0xa6/0x380
   [<c04b3b10>] ? seq_read+0x0/0x380
   [<c04d5d2f>] ? proc_reg_read+0x5f/0x90
   [<c049c4a1>] ? vfs_read+0xa1/0x140
   [<c04d5cd0>] ? proc_reg_read+0x0/0x90
   [<c049c981>] ? sys_read+0x41/0x70
   [<c0402bd0>] ? sysenter_do_call+0x12/0x26

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Michael Rubin <mrubin@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/vmstat.c